WAVEGUIDE ESCALATORS FOR A PHOTONICS CHIP

Structures for a waveguide escalator and methods of forming such structures. A structure comprises a first waveguide core, and a back-end-of-line stack including a first dielectric layer, a second dielectric layer on the first dielectric layer, an opening in the second dielectric layer, a second waveguide core including a section that overlaps with a section of the first waveguide core, and a plurality of third waveguide cores disposed between the section of the first waveguide core and the section of the second waveguide core. The plurality of third waveguide cores are positioned inside the opening in the second dielectric layer, the first dielectric layer comprises a first material with a first refractive index, and the second dielectric layer comprises a second material with a second refractive index different from the first refractive index.